Terpene-Based Spotting Fluid Compositions for Differential Sticking

ABSTRACT

Terpene-based spotting fluid compositions and processes for freeing differentially stuck pipe are provided. A spotting fluid composition includes a terpene and an acid, such that the acid initiates an exothermic polymerization reaction of the terpene. Another spotting fluid composition includes an invert emulsion having a terpene external phase and a non-miscible organic hygroscopic fluid internal phase. The terpene emulsion spotting fluid composition may be introduced downhole in the vicinity of a portion of a differentially stuck pipe such that the spotting fluid composition contacts a filter cake surrounding the portion of the differentially stuck pipe. An acid may be introduced downhole in the vicinity of a portion of a differentially stuck pipe such that the acid initiates an exothermic polymerization reaction of the terpene of the terpene emulsion spotting fluid composition.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application No.62/291,768 filed Feb. 5, 2016, and titled “TERPENE-BASED SPOTTING FLUIDCOMPOSITIONS FOR DIFFERENTIAL STICKING.” For purposes of United Statespatent practice, this application incorporates the contents of theProvisional Application by reference in its entirety.

BACKGROUND Field of the Disclosure

Embodiments of the disclosure generally relate to downhole treatmentfluids and, more specifically, spotting fluids used to freedifferentially stuck pipe in a well.

Description of the Related Art

Drilling and production systems are employed to access and extracthydrocarbons from hydrocarbon reservoirs in geologic formations. Duringthe course of drilling a well, pipe inserted into the well may becomestuck such that the pipe is unable to be rotated or reciprocated.Differentially stuck pipe, such as a drill string or casing, occurs whena pressure differential across a permeable zone of the formation causesa vacuum seal which locks the drill string or casing in place. In someinstances, lubrication fluids, dehydrating agents such as anhydrousglycols, and acids, either alone or in combination, may be used in anattempt to free the differentially stuck pipe. For example, dehydratingagents may be used to dehydrate the filter cake to assist in relivepressure and break the vacuum seal against the permeable zone of theformation.

SUMMARY

Spotting fluids may be used to free differentially stuck pipe (forexample, drill string or casing) in a well. Pipe inserted in a wellboremay become sealed against a geologic formation due to the buildup ofmaterial (for example, a filter cake) around a portion of the pipe. Aspotting fluid is introduced to remove or reduce this seal and free thestuck pipe. However, preparation and use of existing spotting fluids maybe time-consuming and require hours of soak time to be effective. Somespotting fluids may use corrosive fluids to reduce or remove the seal ofthe filter.

Embodiments of the disclosure generally relate to terpene-based spottingfluid compositions for freeing differentially stuck pipe in a well. Morespecifically, embodiments of the disclosure include a spotting fluidcomposition that includes a terpene and an acid (such as a sulfonic acidor a Lewis acid) and a spotting fluid composition that includes aninvert emulsion having a terpene external phase and a non-miscibleorganic hygroscopic fluid internal phase.

In one embodiment, a spotting fluid composition for freeingdifferentially stuck pipe is disclosed that includes an invert emulsion.The invert emulsion has an external phase that includes a terpene and aninternal phase that includes a hygroscopic fluid. In some embodiments,the terpene includes at least one of d-limonene, α-pinene, β-pinene,myrecene, geraniol, carvone, crysanthemic acid, farnesol, humulene,squalene, careen, camphene, α-terpinene, γ-terpinene, and sabinene. Insome embodiments, the terpene is selected from the group consisting ofd-limonene, α-pinene, β-pinene, myrecene, geraniol, carvone,crysanthemic acid, farnesol, humulene, squalene, careen, camphene,α-terpinene, γ-terpinene, and sabinene. In some embodiments, thehygroscopic fluid includes anhydrous glycol. In some embodiments, theterpene consists of d-limonene and the hygroscopic fluid consists ofanhydrous glycol. In some embodiments, the invert emulsion consists ofthe external phase having the terpene and the internal phase having thehygroscopic fluid. In some embodiments, the external phase consists ofthe terpene and the internal phase consists of the hygroscopic fluid. Insome embodiments, the terpene and hygroscopic fluid have a volumetricratio in a range of 7:3 to 8:2. In some embodiments, the spotting fluidcomposition includes a viscosifier. In some embodiments, the spottingfluid composition includes an additive that acts as a wetting agent andan emulsifier.

In another embodiment, a method of freeing a differentially stuck pipein a well is disclosed. The method includes introducing a spotting fluidcomposition in the vicinity of a portion of differentially stuck pipe,such that the spotting fluid contacts a material surrounding the portionof differentially stuck pipe. The spotting fluid composition includes aninternal emulsion having an external phase that includes a terpene andan internal phase that includes a hygroscopic fluid. In someembodiments, the terpene may include at least one of d-limonene,α-pinene, β-pinene, myrecene, geraniol, carvone, crysanthemic acid,farnesol, humulene, squalene, careen, camphene, α-terpinene,γ-terpinene, and sabinene. In some embodiments, the terpene is selectedfrom the group consisting of d-limonene, α-pinene, β-pinene, myrecene,geraniol, carvone, crysanthemic acid, farnesol, humulene, squalene,careen, camphene, α-terpinene, γ-terpinene, and sabinene. The methodfurther includes allowing the spotting fluid composition to interactwith the material surrounding the portion of differentially stuck pipeover a time period. The method also includes introducing a sulfonic acidin the vicinity of a portion of differentially stuck pipe such that thesulfonic acid contacts the spotting fluid composition and initiates apolymerization reaction of the terpene. In some embodiments, thepolymerization reaction generates a temperature differential of up to300° F. In some embodiments, the sulfonic acid includesdodecyibenzenesulfonic acid (DDBSA). In some embodiments, the methodincludes introducing a Lewis acid in the vicinity of a portion ofdifferentially stuck pipe such that the Lewis acid contacts the spottingfluid composition and initiates a polymerization reaction of theterpene. In some embodiments, the hygroscopic fluid includes anhydrousglycol. In some embodiments, the external phase consists of a terpeneand the internal phase consists of a hygroscopic fluid. In someembodiments, the invert emulsion consists of the external phase thatincludes the terpene and the internal phase that includes thehygroscopic fluid. In some embodiments, the terpene consists ofd-limonene and the hygroscopic fluid consists of anhydrous glycol. Insome embodiments, the spotting fluid composition includes a viscosifier.In some embodiments the spotting fluid composition includes an additivethat acts as a wetting agent and an emulsifier.

Additionally, in another, a method of forming a spotting fluidcomposition for freeing differentially stuck pipe is provided. Themethod includes providing an invert emulsion having an external phasethat includes a terpene and an internal phase that includes ahygroscopic fluid. In some embodiments, the terpene may include at leastone of: d-limonene, α-pinene, β-pinene, myrecene, geraniol, carvone,crysanthemic acid, farnesol, humulene, squalene, careen, camphene,α-terpinene, γ-terpinene, and sabinene. In some embodiments, the terpeneis selected from the group consisting of d-limonene, α-pinene, β-pinene,myrecene, geraniol, carvone, crysanthemic acid, farnesol, humulene,squalene, careen, camphene, α-terpinene, γ-terpinene, and sabinene. Insome embodiments, the hygroscopic fluid includes anhydrous glycol. Insome embodiments, the terpene consists of d-limonene and the hygroscopicfluid consists of anhydrous glycol. In some embodiments, the invertemulsion includes the external phase that includes the terpene and theinternal phase that includes the hygroscopic fluid. In some embodiments,the external phase consists of the terpene and the internal phaseconsists of the hygroscopic fluid. In some embodiments, the methodincludes adding a viscosifier to the invert emulsion. In someembodiments, the method includes adding an additive to the invertemulsion, the additive acting as a wetting agent and an emulsifier. Insome embodiments, the method includes adding a lubricant to the invertemulsion.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood with regard to the followingdescriptions, claims, and accompanying drawings. It is to be noted,however, that the drawings illustrate only several embodiments of theinvention and are therefore not to be considered limiting of theinvention's scope as it can admit to other equally effectiveembodiments.

FIG. 1 is a plot showing the temperature increase of an exothermicreaction between a terpene (d-limonene) and dodecylbenzenesulfonic acid(DDBSA) in accordance with an embodiment of the disclosure; and

FIG. 2 is a block diagram of a process for freeing differentially stuckpipe using a terpene emulsion spotting fluid composition in accordancewith an embodiment of the disclosure.

DETAILED DESCRIPTION

The present disclosure will now be described more fully with referenceto the accompanying drawings, which illustrate embodiments of theinvention. This invention may, however, be embodied in many differentforms and should not be construed as limited to the illustratedembodiments set forth in the disclosure. Rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art.

The present disclosure includes compositions for use as spotting fluidsand methods to free differentially stuck pipe in a well. The spottingfluid compositions and methods described in this disclosure may freedifferentially stuck pipe by removing or reducing the seal against aformation by material (for example, a filter cake) around thedifferentially stuck pipe. In some embodiments, the spotting fluidcompositions and methods may remove or reduce the seal using anexothermic polymerization reaction to generate heat. Additionally, insome embodiments, the spotting fluid compositions and methods describedin this disclosure may also lubricate the material around thedifferentially stuck pipe, dehydrate the material around thedifferentially stuck pipe, or both.

The present disclosure includes spotting fluid compositions having aterpene and an acid, and spotting fluid compositions having terpeneinvert emulsions. As used in this disclosure, the term “terpene” mayinclude compounds described as “terpanoids.” In alternate embodiments ofthe disclosure, terpenoids that are suitable for use in the spottingfluid compositions described in this disclosure may be used based onsuitable solvency and reactivity properties.

In some embodiments, a terpene and acid spotting fluid composition maybe used to free differentially stuck pipe by using the heat generatedfrom the exothermic polymerization reaction of the terpene and the acid.In some embodiments, a terpene may be introduced downhole in the in thevicinity of a differentially stuck pipe. After the terpene is introduceddownhole, an acid may be introduced downhole to initiate the exothermicpolymerization reaction and generate heat to remove or reduce the sealof material around the differentially stuck pipe and free the pipe. Insome embodiments, the terpene and acid may be mixed on the surface toform the spotting fluid composition before introduction downhole.

In some embodiments, a terpene emulsion spotting fluid composition maybe formed from an invert emulsion having a terpene external phase and anon-miscible organic hygroscopic fluid. In some embodiments, the terpeneemulsion fluid composition may be introduced downhole in the in thevicinity of a differentially stuck pipe. In some embodiments, theterpene emulsion spotting fluid composition may be allowed to soak for atime period, such as to lubricate the material around the differentiallystuck pipe, dehydrate the material around the differentially stuck pipe,or both. After the terpene emulsion fluid composition is downhole, anacid may be subsequently introduced downhole to initiate an exothermicpolymerization reaction of the terpene and generate heat to remove orreduce the seal of material around the differentially stuck pipe.

EXAMPLES

The following examples are included to demonstrate embodiments of thedisclosure. It should be appreciated by those of skill in the art thatthe techniques and compositions disclosed in the example which followsrepresents techniques and compositions discovered by the inventors tofunction well in the practice of the invention, and thus can beconsidered to constitute modes for its practice. However, those of skillin the art should, in light of the present disclosure, appreciate thatmany changes can be made in the specific embodiments which are disclosedand still obtain a like or a similar result without departing from thespirit and scope of the invention.

The following non-limiting examples of spotting fluid compositions weretested and compared against a baseline mud. Table 1 shows theformulation of the baseline mud used in the differential stickingtesting:

TABLE 1 Baseline Mud for Differential Sticking Testing Water 0.95 oilbarrels (bbl) Bentonite 25 pound/oil barrels (lb/bbl) Caustic Soda 1lb/bbl Lignosulfonate 5 lb/bbl

Table 2 shows the formulation of a first spotting fluid composition(Spotting Fluid A) used in the differential sticking testing. The firstspotting fluid is formed from an invert emulsion having a terpeneexternal phase and a non-miscible organic hygroscopic fluid internalphase. The first spotting fluid includes EZ-Mul® wettingagent/emulsifier (that is, an additive that acts as both a wetting agentand an emulsifier) manufactured by Halliburton of Houston, Tex., USA,and VG-69® organophilic clay viscosifier manufactured by M-I Swaco ofPleasanton, Tex., USA:

TABLE 2 Spotting Fluid A for Differential Sticking Testing Limonene 0.7bbl Glycerin 0.3 bbl EZ-Mul ® 1 lb/bbl VG-69 ® 6 lb/bbl

Table 3 shows the formulation of a second spotting fluid composition(Spotting Fluid B) used in the differential sticking testing. The secondspotting fluid is formed from a terpene and a sulfonic acid:

TABLE 3 Spotting Fluid B for Differential Sticking Testing Limonene 0.9bbl DDBSA 0.1 bbl

Table 4 shows the formulation of a third spotting fluid composition(Spotting Fluid C) used in the differential sticking testing. The thirdspotting fluid is formed from an invert emulsion having a terpeneexternal phase and a non-miscible organic hygroscopic fluid internalphase. The third spotting fluid includes Versawet® organic surfactant,Versacoat® organic surfactant, and Verasamul® multi-purpose emulsifiermanufactured by manufactured by M-I Swaco of Pleasanton, Tex., USA andEstaDril 4000 manufactured by Croda International plc of Snaith, UK:

TABLE 4 Spotting Fluid C for Differential Sticking Testing Limonene 0.61bbl Versawet ® 8.8 lb/bbl Versacoat ® 8.8 lb/bbl Versamul ® 4.3 lb/bblEstadril 4000 ® 22.5 lb/bbl Lime 11.1 lb/bbl Graphite powder 13.8 lb/bblGlycerin 0.21 bbl Barite 25.5 lb/bbl

Table 5 shows the formulation of a fourth spotting fluid composition(Spotting Fluid D) used in the differential sticking testing. The fourthspotting fluid is formed from an invert emulsion having a terpeneexternal phase and a non-miscible organic hygroscopic fluid internalphase. The fourth spotting fluid includes Versawet® organic surfactant,Versacoat® organic surfactant, and Verasamul® multi-purpose emulsifiermanufactured by manufactured by M-I Swaco of Pleasanton, Tex., USA andEstaDril 4000 manufactured by Croda International plc of Snaith, UK:

TABLE 5 Spotting Fluid D for Differential Sticking Testing Limonene 0.60bbl Versawet ® 8.6 lb/bbl Versacoat ® 8.6 lb/bbl Versamul ® 4.3 lb/bblEstadril 4000 ® 21.6 lb/bbl Lime 10.8 lb/bbl Graphite powder 13.5 lb/bblSodium chloride 17.5 lb/bbl Water 0.21 bbl Barite 24.8 lb/bbl

Table 6 shows the formulation of a fifth spotting fluid composition(Spotting Fluid E) used in the differential sticking testing. The fifthspotting fluid is formed from an emulsion having a terpene internalphase and water as the external phase. The fifth spotting fluid includesTween 80® and Span 85® manufactured by Croda International plc ofSnaith, UK. Spotting Fluid E was prepared by blending DDBSA in a mixerfor 5 minutes before addition to the spotting fluid:

TABLE 6 Spotting Fluid E for Differential Sticking Testing Water 0.78bbl Tween 80 7.6 lb/bbl Span 85 7.6 lb/bbl Limonene 0.13 bbl Defoamer(silicone) 1.2 lb/bbl DDBSA 15.2 lb/bbl

The baseline mud, Spotting Fluid A, Spotting Fluid B, Spotting Fluid C,Spotting Fluid D, and Spotting Fluid E were tested using the followingdifferential sticking test procedure using a differential stickingtester (also referred to as a “stickometer”) having a filtration cell toenable deposition of a filter cake and a plate pressed under load ontothe filter cake:

1. Prepare baseline mud;

2. Fill Fann stickometer to a scored line, apply 500 psi of pressure,and open the collector to obtain 10 ml of filtrate;

3. At 10 ml of filtrate, apply about 80 lb of force to the plate for 2minutes to allow for sticking onto the filter cake;

4. Allow additional 2 ml of filtrate to be collected;

5. To obtain baseline mud data, allow filtering for about 16 hours, thenobtain torque-to-free measurements by using a torque gauge three timesand calculating the average torque;

6. To obtain spotting fluid data, depressurize the cell and dissemble toallow the plate to remain suck in the filter cake. Decant off the fluidand place the spotting fluid into the stickometer and repressurize to500 psi;

7. Allow filtering for about 16 hours or until complete and then obtaintorque-to-free measurements by using a torque gauge three times andcalculating the average torque.

The results of the differential sticking test procedure for the baselinemud, Spotting Fluid A, Spotting Fluid B, Spotting Fluid C, SpottingFluid D, and Spotting Fluid E are shown in Table 7:

TABLE 7 Differential Sticking Testing results Torque to free(inches/pound % Fluid (in/lb)) Improvement Baseline Mud 190 SpottingFluid A (16 hours) 143 25% Spotting Fluid B (30 minutes) 100 47%Spotting Fluid B (9 hours) 0 (9 hr fluid blowout, 100%  plate completelyfreed from filter cake) Spotting Fluid C (16 hours) 150 21% SpottingFluid D (16 hours)  5 97% Spotting Fluid E (16 hours) 0 (16 hr fluidblowout, 100%  plate completely freed from filter cake)

As shown in Table 4, an example terpene emulsion spotting fluidcomposition having a terpene external phase (Spotting Fluid A) shows a25% reduction in torque-to-free the test plate from the test filter cakeafter a 16 hour time period. As also shown in Table 4, an exampleterpene and acid spotting fluid composition (Spotting Fluid B) shows a47% reduction in torque -to-free the test plate from the filter cakeafter a 30 minute time period and completely frees the test plate fromthe filter cake after a 9 hour time period. In another example, anotherterpene emulsion spotting fluid composition having a terpene externalphase (Spotting Fluid C) shows a 21% reduction in torque-to-free after a16 hour time period. In yet another example, another terpene emulsionspotting fluid composition having a terpene external phase (SpottingFluid D) shows a 97% reduction in torque-to-free after a 16 hour timeperiod. Finally, an example terpene emulsion spotting fluid compositionhaving a terpene internal phase (Spotting Fluid E) completely frees thetest plate from the filter cake after a 16 hour time period.

Terpene and Acid Spotting Fluid Compositions

In some embodiments, a terpene-based spotting fluid composition mayinclude a terpene and a sulfonic acid. In some embodiments, the terpenemay include d-limonene, α-pinene, β-pinene, myrecene, geraniol, carvone,crysanthemic acid, farnesol, humulene, squalene, careen, camphene,α-terpinene, γ-terpinene, and sabinene. In some embodiments, thesulfonic acid may include dodecylbenzenesulfonic acid (DDBSA),methanesulfonic acid (MsOH), benzene sulfonic acid, other suitable alkylsulfonic acids, and other suitable alkaryl sulfonic acids. In someembodiments, the spotting fluid composition may be formed fromd-limonene and DDBSA. In other embodiments, a heat generating spottingfluid composition may include a terpene and an inorganic acid such assulfuric acid and nitric acid.

In some embodiments, a terpene and acid spotting fluid composition maybe formed by introducing (for example, pumping) the terpene base fluiddownhole, such as in a pill, following by introducing (for example,pumping) a relatively thin spacer fluid downhole, then by introducing(for example, pumping) an organic acid downhole. As used herein, theterm “spacer fluid” refers to a fluid which can be viscosified andweighted. In some embodiments, the spacer fluid may include waterviscosified with clays, natural gums (such as guar or xanthan), andpolymers (such as partially hydrolyzed polyacrylamide (PHPA)). In someembodiments, the spacer fluid may include organic based spacer fluids,such as viscosified diesel/mineral oil with oil based viscosifiers suchas aluminum stearates, styrenic polymers (styrene acrylates,carboxylated styrene butadienes, styrene butadienes and the like). Insome embodiments, the spacer fluid may include weighting agents such ascalcium carbonate, barite, hematite, and other suitable weightingagents.

Alternatively, in some embodiments, a terpene and acid spotting fluidcomposition may be formed on the surface before being introduceddownhole, such as by mixing the terpene and the organic acid. Theterpene and organic acid initiates an exothermic polymerization reactionof the terpene to generate heat to free the differentially stuck pipe.

In some embodiments, the exothermic reaction may reach up to 300° F.differential temperature generation. As used in the disclosure, the term“differential temperature” refers to a maximum temperature value minus astarting temperature value. FIG. 1 is a plot 100 showing the temperatureincrease (line 102) of an exothermic reaction between a terpene(d-limonene) and DDBSA in accordance with an embodiment of thedisclosure. As shown in FIG. 1, the Y-axis 104 corresponds to thetemperature of the d-limonene and DDBSA mixture and the X-axis 106corresponds to the elapsed time. In one non-limiting example, 50milliliters (ml) of d-limonene was placed in a beaker having a magneticstir bar for agitation set to 400 revolutions-per-minute (rpm) on a stirplate. The temperature increase was measured by taking temperaturemeasurements over a time period of 0 to 3000 seconds. As shown in FIG.1, after 50 seconds for temperature stabilization, 4 ml of DDBSA wasinjected into the d-limonene at point 108.

As shown in FIG. 1, an initial exotherm occurred from 75° F. to 100° F.After 5 seconds of a relatively slow exothermic reaction, a relativelyfast exotherm and associated temperature increase occurred from 100° F.to 400° F., after which the mixture began to cool after polymerizationof the d-limonene. As shown in FIG. 1, the cooling occurred over time toless than 100° F.

In another embodiment, a terpene and acid spotting fluid composition mayinclude a terpene base fluid and an initiator solution having a Lewisacid. In such embodiments, the terpene may include d-limonene, α-pinene,β-pinene, myrecene, geraniol, carvone, crysanthemic acid, farnesol,humulene, squalene, careen, camphene, α-terpinene, γ-terpinene, andsabinene. In some embodiments, the Lewis acid may include titaniumtetrachloride (TiCl₄), boron trifluoride (BF₃), tin tetrachloride(SnCl₄), and aluminum chloride (AlCl₃). Here again, in some embodiments,a terpene and acid spotting fluid composition may be formed byintroducing (for example, pumping) the terpene base fluid downhole, suchas in a pill, following by introducing (for example, pumping) arelatively thin spacer fluid downhole, then by introducing (for example,pumping) the initiator solution having the Lewis acid downhole. In someembodiments, the spacer fluid may include water viscosified with clays,natural gums (such as guar or xanthan), and polymers (such as partiallyhydrolyzed polyacrylamide (PHPA)). In some embodiments, the spacer fluidmay include organic based spacer fluids, such as viscosifieddiesel/mineral oil with oil based viscosifiers such as aluminumstearates, styrenic polymers (styrene acrylates, carboxylated styrenebutadienes, styrene butadienes and the like). In some embodiments, thespacer fluid may include weighting agents such as calcium carbonate,barite, hematite, and other suitable weighting agents.

Alternatively, in some embodiments, the terpene and initiator solutionhaving the Lewis acid may be formed on the surface before beingintroduced downhole. The terpene and Lewis acid of the initiatorsolution initiates an exothermic polymerization reaction of the terpeneto generate heat to free the differentially stuck pipe.

Terpene Emulsion Spotting Fluid Compositions

In some embodiments, a spotting fluid composition may include an invertemulsion having a terpene as an external phase and a non-miscibleorganic hygroscopic fluid as a dehydrating internal phase. In someembodiments, the terpene external phase may include d-limonene,α-pinene, β-pinene, myrecene, geraniol, carvone, crysanthemic acid,farnesol, humulene, squalene, careen, camphene, α-terpinene,γ-terpinene, and sabinene. In some embodiments, the non-miscible organichygroscopic fluid may include anhydrous glycol (also referred to as“glycerine” or “glycerin”). In some embodiments, the spotting fluidcomposition may be an invert emulsion having d-limonene as the externalphase and anhydrous glycol as the internal phase. In some embodiments,the internal phase may include a saturated brine (for example, saturatedcalcium chloride) or a combination of a saturated brine and anon-miscible organic hygroscopic fluid such as anhydrous glycol. Forexample, in some embodiments a spotting fluid composition may include aninvert emulsion having a terpene as an external phase and a sodiumchloride brine as an internal phase.

In some embodiments, the spotting fluid composition of an invertemulsion having a terpene and a non-miscible organic hygroscopic fluidmay be reacted with an organic acid or a Lewis acid downhole to generateheat to further assist in freeing differentially stuck pipe. In someembodiments, the heat generating spotting fluid composition of an invertemulsion having a terpene as an external phase and a non-miscibleorganic hygroscopic fluid as a dehydrating internal phase may beintroduced (for example, pumped) downhole, followed by an organic acidor Lewis acid introduced (for example, pumped) downhole. As describedsupra, the heat generating spotting fluid composition and the organicacid or Lewis acid initiates an exothermic polymerization reaction ofthe terpene to release heat to free the differentially stuck pipe. Insome embodiments, as shown in FIG. 1 and as discussed supra, theexothermic polymerization reaction of the terpene of the spotting fluidcomposition may reach up to 300° F. differential temperature generation.

In some embodiments, the invert emulsion of the spotting fluidcomposition may have terpene to non-miscible organic hygroscopic fluidvolumetric ration of 7:3. In some embodiments, the invert emulsion ofthe spotting fluid composition may have a terpene to non-miscibleorganic hygroscopic fluid volumetric ration of 6:4. In some embodiments,the invert emulsion of the spotting fluid composition may have terpeneto non-miscible organic hygroscopic fluid volumetric ratio of 8:2. Insome embodiments, the invert emulsion of the spotting fluid compositionmay have terpene to non-miscible organic hygroscopic fluid volumetricratio from about 7:3 to about 8:2.

In some embodiments, a spotting fluid composition may include anemulsion having a terpene as an internal phase and water as an externalphase. In some embodiments, the terpene internal phase may included-limonene, α-pinene, β-pinene, myrecene, geraniol, carvone,crysanthemic acid, farnesol, humulene, squalene, careen, camphene,α-terpinene, γ-terpinene, and sabinene. In some embodiments, thespotting fluid composition may be an emulsion having d-limonene as theinternal phase and water as the external phase.

In some embodiments, a terpene emulsion spotting fluid composition mayinclude a wetting agent/emulsifier and a viscosifier. In someembodiments, the wetting agent/emulsifier may include fatty acids,modified fatty acids, fatty amide condensates, imidazolines, ethoxylatedsorbitan, and other suitable wetting agents/emulsifiers. In someembodiments, the viscosifier may include aluminum soaps, styrenebutadiene latexes, styrene butadiene resins, carboxylated styrenebutadienes, styrene acrylates, and other suitable viscosifiers. In someembodiments, a terpene emulsion spotting fluid composition may include awetting agent/emulsifier additive and a clay additive. In someembodiments, a terpene emulsion spotting fluid composition may be formedfrom an invert emulsion having a terpene as an external phase and anon-miscible organic hygroscopic fluid as an internal phase, a wettingagent/emulsifier, and a clay. For example, in such embodiments, aspotting fluid composition may be formed from an invert emulsion havingd-limonene as an external phase and anhydrous glycol as an internalphase, a wetting agent/emulsifier and a viscosifier

In some embodiments, the terpene emulsion spotting fluid composition mayinclude a lubricant. For example, in some embodiments, the lubricant mayinclude glycerol esters, polyalphaolefins, phosphate esters, and othersuitable lubricants. In some embodiments, the terpene emulsion spottingfluid composition may include lime (calcium hydroxide).

FIG. 2 depicts a process 200 for using a terpene emulsion spotting fluidcomposition in accordance with an embodiment of the disclosure. In someembodiments, a spotting fluid composition having an invert emulsion of aterpene and a non-miscible organic hygroscopic fluid may be introduced(for example, by pumped downhole) in the vicinity of a differentiallystuck pipe (block 202). In some embodiments, the spotting fluidcomposition may be allowed to soak for a time period (block 204). Forexample, the spotting fluid composition may interact with the material(for example, filter cake) surrounding the stuck pipe.

In some embodiments, the spotting fluid composition may free thedifferentially stuck pipe after a soaking time period without the use ofheat generated from an exothermic reaction. In such embodiments, theprocess 200 may not include the addition of an organic acid or a Lewisacid as further described.

After a soaking time period, an organic acid or a Lewis acid may beintroduced (for example, pumped) downhole in the vicinity of adifferentially stuck pipe (block 206). As described supra, the reactionbetween the terpene and the organic acid or Lewis acid produces heat toremove or reduce the seal of the material around the differentiallystuck pipe (block 208). The freed pipe may then be moved, such as byremoving the freed pipe from the wellbore (block 210).

In some embodiments, the spotting fluid compositions described in thedisclosure may be used as fluid pills. In some embodiments, the spottingfluid compositions may include other monomers subject to exothermicpolymerization reactions, such as acrylates, acrylamides, styrene, andother suitable monomers with initiators such as acid, caustic, andradical generation azo compounds and peroxides.

Ranges may be expressed in the disclosure as from about one particularvalue, to about another particular value, or both. When such a range isexpressed, it is to be understood that another embodiment is from theone particular value, to the other particular value, or both, along withall combinations within said range.

Throughout this application, where patents or publications arereferenced, the disclosures of these references in their entireties areintended to be incorporated by reference into this application, in orderto more fully describe the state of the art to which the disclosurepertains, except when these references contradict the statements made inthe disclosure.

Further modifications and alternative embodiments of various aspects ofthe disclosure will be apparent to those skilled in the art in view ofthis description. Accordingly, this description is to be construed asillustrative only and is for the purpose of teaching those skilled inthe art the general manner of carrying out the embodiments described inthe disclosure. It is to be understood that the forms shown anddescribed in the disclosure are to be taken as examples of embodiments.Changes may be made in the elements described in the disclosure withoutdeparting from the spirit and scope of the disclosure as described inthe following claims. Headings used in the disclosure are fororganizational purposes only and are not meant to be used to limit thescope of the description.

What is claimed is:
 1. A spotting fluid composition for freeingdifferentially stuck pipe in a well, the spotting fluid compositioncomprising: an invert emulsion including: an external phase comprising aterpene; and an internal phase comprising a hygroscopic fluid.
 2. Thespotting fluid composition of claim 1, wherein the terpene comprises atleast one of: d-limonene, α-pinene, β-pinene, myrecene, geraniol,carvone, crysanthemic acid, farnesol, humulene, squalene, careen,camphene, α-terpinene, γ-terpinene, and sabinene.
 3. The spotting fluidcomposition of claim 1, wherein the terpene is selected from the groupconsisting of d-limonene, α-pinene, β-pinene, myrecene, geraniol,carvone, crysanthemic acid, farnesol, humulene, squalene, careen,camphene, α-terpinene, γ-terpinene, and sabinene.
 4. The spotting fluidcomposition of claim 1, wherein the hygroscopic fluid comprisesanhydrous glycol.
 5. The spotting fluid composition of claim 4, whereinthe terpene consists of d-limonene and the hygroscopic fluid consists ofanhydrous glycol.
 6. The spotting fluid of claim 1, wherein the invertemulsion consists of: the external phase comprising the terpene; and theinternal phase comprising the hygroscopic fluid.
 7. The spotting fluidcomposition of claim 1, wherein the terpene and hygroscopic fluid have avolumetric ratio in a range of 7:3 to 8:2.
 8. The spotting fluidcomposition of claim 1, comprising a viscosifier.
 9. The spotting fluidcomposition of claim 1, comprising an additive that acts as a wettingagent and an emulsifier.
 10. The spotting fluid composition of claim 1,comprising a lubricant.
 11. A method of freeing differentially stuckpipe in a well, comprising: introducing a spotting fluid composition inthe vicinity of a portion of differentially stuck pipe, such that thespotting fluid contacts a material surrounding the portion ofdifferentially stuck pipe, the spotting fluid composition comprising: aninvert emulsion including: an external phase comprising a terpene; andan internal phase comprising a hygroscopic fluid.
 12. The method ofclaim 11, wherein the terpene comprises at least one of: d-limonene,α-pinene, β-pinene, myrecene, geraniol, carvone, crysanthemic acid,farnesol, humulene, squalene, careen, camphene, α-terpinene,γ-terpinene, and sabinene.
 13. The method of claim 11, comprisingallowing the spotting fluid composition to interact with the materialsurrounding the portion of differentially stuck pipe over a time period.14. The method of claim 11, comprising introducing a sulfonic acid inthe vicinity of a portion of differentially stuck pipe such that thesulfonic acid contacts the spotting fluid composition and initiates apolymerization reaction of the terpene.
 15. The method of claim 14,wherein the polymerization reaction generates a temperature differentialof up to 300° F.
 16. The method of claim 14, wherein the sulfonic acidcomprises dodecylbenzenesulfonic acid (DDBSA).
 17. The method of claim11, comprising introducing a Lewis acid in the vicinity of a portion ofdifferentially stuck pipe such that the Lewis acid contacts the spottingfluid composition and initiates a polymerization reaction of theterpene.
 18. The method of claim 11, wherein the hygroscopic fluidcomprises anhydrous glycol.
 19. The method of claim 11, wherein theinvert emulsion consists of: the external phase comprising the terpene;and the internal phase comprising the hygroscopic fluid.
 20. The methodof claim 11, wherein the terpene consists of d-limonene and thehygroscopic fluid consists of anhydrous glycol.
 21. The method of claim11, wherein the spotting fluid composition comprises a viscosifier. 22.The method of claim 11, wherein the spotting fluid composition comprisesan additive that acts as a wetting agent and an emulsifier.
 23. Themethod of claim 11, wherein the spotting fluid composition comprises alubricant.
 24. A method of forming a spotting fluid composition forfreeing differentially stuck pipe, comprising: providing an invertemulsion, the invert emulsion including: an external phase comprising aterpene; and an internal phase comprising a hygroscopic fluid.
 25. Themethod of claim 24, wherein the terpene comprises at least one of:d-limonene, α-pinene, β-pinene, myrecene, geraniol, carvone,crysanthemic acid, farnesol, humulene, squalene, careen, camphene,α-terpinene, γ-terpinene, and sabinene.
 26. The method of claim 24,wherein the terpene is selected from the group consisting of d-limonene,α-pinene, β-pinene, myrecene, geraniol, carvone, crysanthemic acid,farnesol, humulene, squalene, careen, camphene, α-terpinene,γ-terpinene, and sabinene.
 27. The method of claim 24, wherein thehygroscopic fluid comprises anhydrous glycol.
 28. The method of claim27, wherein the terpene consists of d-limonene and the hygroscopic fluidconsists of anhydrous glycol.
 29. The method of claim 24, wherein theinvert emulsion consists of: the external phase comprising the terpene;and the internal phase comprising the hygroscopic fluid.
 30. The methodof claim 24, comprising adding a viscosifier to the invert emulsion. 31.The method of claim 24, comprising adding an additive to the invertemulsion, the additive acting as a wetting agent and an emulsifier. 32.The method of claim 24, comprising adding a lubricant to the invertemulsion.